USPTO Patents Application 09775169

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APPLICATION FOR
UNITED STATES LETTERS PATENT

Title: SUPPRESSION OF CURSOR CONTROL DURING TACTILE FEEDBACK
OPERATION

Inventors: Steven L. Steinbrunner

Eric B. Taylor

Thomas H. Tichy

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Background of the Invention

Computers use various cursor control mechanisms to provide a physical control
over cursor placement on the computer screen. The most common form of cursor control
device is a mouse. The mouse includes a plurality of buttons to allow the user to select

5 various items on the screen. When the user depresses the mouse button, the switch inside
provides a tactile feedback to the user commonly referred to as a "mouse click."

Because a mouse is used in a position physically remote from the computer, it is
not the preferred cursor control device for portable or laptop computers. In these
computers, users want the freedom to operate the computer without any additional

10 external devices. One frequently used cursor control mechanism incorporated into
portable computers is that of a pointing stick. These devices have been described in
many patents including U.S. Patent Number 5,966,117 to Seffernick incorporated herein
by reference. The Seffernick device provides a pointing stick mechanism including the
ability for sensing a z-axis deflection. This z-axis deflection can be used to provide the

15 mouse click function in place of providing separate buttons on the chassis of the
computer. However, the pointing stick of Seffernick does not provide any tactile
feedback to the user indicating that a click has occurred and is therefore not ideal.

The present invention overcomes this problem by providing a tactile feedback that
can be easily provided with a pointing stick. The present invention also provides a

20 mechanism for providing tactile feedback to the user for other conditions as desired by
software within the computer.

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Description of the Drawings:

Figure 1 shows a computer device incorporating the present invention
Figure 2 shows a pointing stick according to the present invention.
Figure 3 shows a pzt assembly according to the present invention.
5 Figure 4 shows a block diagram of an electrical circuit for activating the pzt assembly.
Figure 5 shows a circuit diagram for driving the feedback device according to the present
invention.

Figure 6 shows a standard computer mouse incorporating the present invention.

1 0 Detailed Description

Computers typically are controlled by users through the use of various input
control devices including a cursor control and keyboard. Computer 7 typically has a
program running thereon that provides for movement of a cursor 8 on display device 1 1
in response to the user operating cursor control device 9. One such program is Microsoft

15 Windows 98. Display device 1 1 can be any of a number of different devices, such as an
LCD attached to a laptop computer; other similar devices such as a computer monitor
employing a cathode ray tube (CRT) may also be used. Cursor control device 9 as shown
in FIG. 1 is a pointing stick, although the invention is not limited to any particular
pointing device. For example, cursor control device 9 may also be a mouse, joystick,

20 wheel, trackball, or a touch pad. As shown in FIG. 1, cursor control device 9 is a
pointing stick mounted between the "g" "h" and "b" keys on a standard "QWERTY"
keyboard.

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Cursor control device 9 allows a computer user to move the cursor 8 on display
device 11. Cursor control device 9 therefore translates movement by the user into an
electronic signal sent to the computer via a communications link which is internal to the
computer 7 of FIG. L

5 Not shown is that computer 7 typically includes a central-processing unit (CPU),

a random-access memory (RAM), and a read-only memory (ROM). The CPU,
RAM, and ROM may be of any type; the invention is not particularly limited. In one
embodiment, the CPU is an Intel Pentium processor, there are sixtyfour
megabytes of RAM, and the ROM contains such functionality as a basic input/output

10 system (BIOS). Also not shown is that computer 7 also usually comprises a

fixed storage device such as a hard disk drive with software resident thereon, and a
removable storage device such as a floppy disk drive.

Referring to Fig. 2, a pointing stick 10 according to the present invention is
shown. In particular, the pointing stick 10 is made up of a shaft 12, a substrate 14 for

15 supporting the shaft 12 and a cavity 16 formed in the substrate 14 for placement of a
flexible cable 18 that is electrically connected to four strain gages a,b,c,d located on the
sides of the shaft 12. The shaft 12 may be made of alumina ceramic material or the like.
Typically, the cable 18 may be made of polyamide material containing electrical traces
thereon. Typically, the pointing stick 10 has a rubber-like cap 25 positioned over the top

20 of the shaft 12 to increase the ease of operation. The cap 25 is designed to enable the
operator to control the cursor with a single finger positioned on top of it and pushing in a
direction corresponding to the desired direction of the cursor. The finger pressure places
strain on the shaft 12 that is sensed by the strain gages a,b,c,d. The output from the strain

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gages a,b,c,d can be used to sense a desired movement by the user in the x- or y-axis.
Additionally, using the invention described in U.S. Patent No. 5,966,117, movement in
the z-axis can be sensed.

The tactile assembly 40 is attached to the bottom of the pointing stick 10. The

5 tactile assembly comprises a piezo-electric (pzt) material 42. The pzt material is lead
zironate and lead titanate in addition to other dopants as will be known by those skilled in
the art. The material is pressed in powder form under extremely high pressure and then
fired at 1250 °C. A high voltage is then applied across the material. This aligns the
molecular domains and is commonly referred to as poling. This creates a block of pzt

10 ceramic material which is then machined into wafers. The wafer can then be bonded to a
semi-rigid substrate such as metal, plastic or alumina using an adhesive such as epoxy.

When an electrical power source (not shown) is connected to this material, it
changes physical dimensions in that the wafer will either increase in size with a
corresponding decrease in thickness or, with the opposite polarity electrical signal, it will

15 decrease in size with a corresponding increase in thickness. If the piezo-electric material
42 is attached to a semi-rigid material 44 such as being bonded to a metal substrate, the
entire surface bows or deforms. This is similar in action to the effect of two materials
being bonded together with differing thermal coefficients; the difference causes the
assembly to warp as temperature is varied. As shown in Fig. 3, as the electric power

20 source is applied via terminals x,y, the entire piece of material flexes in an upward

direction 47; when the reverse power is applied, the material deforms in the opposite or
downward direction 49. If the flexing in opposite directions occurs rapidly, it produces a
vibration. By controlling the frequency of an ac power source connected via terminals

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x,y applied to the piezo-electric material 42, the frequency of the vibration can be
controlled. Through experimentation, it has been found that a frequency of
approximately 350 hz yields a vibration that can be easily felt by the user. While the
invention is generally described using a circular pzt material, other forms could also be

5 used including a square or rectangular structure.

The piezo-electric material 42 mounted to the semi-rigid material 44 is
mechanically coupled to the pointing stick 10. As shown in Fig. 2, the material is
mounted via stand-offs 22,24 which maintain a slight separation between the tactile
assembly 40 and the substrate 14. This prevents the substrate from impeding the

10 vibration of the tactile assembly 40. The stand-offs 22,24 also provide the mechanical
coupling to deliver the vibration through the substrate 14 and along the shaft 12 to the
user. The physical attachment mechanism may be accomplished through any common
connection mechanism such as screws, bolts, rivets, etc. While some adhesives could be
used, it is important to select one that will not dampen the vibrations to a point where the

15 user will no longer feel them. The pzt material can also be mounted in other ways,

provided the mechanical coupling of the vibration is accomplished. Thus, for example,
the pzt material could be mounted to the substrate 14 further away from the shaft 12 of
the pointing stick 10. The tactile assembly 40 could also be mounted directly to the shaft
12 of the pointing stick 10 without the use of stand-offs 22,24, provided the piezo-electric

20 material 42 was cantilevered out beyond the edge of the shaft 12 to allow for the flexing
to produce the required vibration. The pzt material could also b ebonded to other layers
of pzt material and this multi-layer package could be used as the substrate 14.

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A driver circuit 50 for providing the ac signal to the tactile assembly 40 is shown
in Fig. 4. The computer dc power source of 12 volts 52 is provided to the circuit 50. This
input is then put through a conversion to provide an ac signal 54 of 24 volts peak to peak
operating at approximately 350 Hz. This is the desired input range to the piezo-electric

5 material 42. The ac signal 54 is then applied to the piezo-electric material 42 upon
receiving an input signal 56 from another source. This input signal 56 may be provided
either directly through sensing a z-axis deflection (which corresponds to a mouse-click)
or through software resident in the computer 1. Once the input signal 56 is provided, it
activates a switch circuit 58 which turns on the ac signal 54 for a limited, predetermined

10 period of time. It has been found that approximately one second is a time sufficient to
provide the desired feedback to the user without unduly interfering with the use of the
computer.

This driver circuit 50 is shown in more detail in Fig. 5. The 12 volt power supply
52 from the computer first goes into a square wave generator 76. The square wave

15 generator 76 consists of an inverter 78 with a feedback resistor 80 and capacitor 82. By
varying the values of feedback resistor 80 and capacitor 82, the frequency of the square
wave 84 can be adjusted. To achieve a frequency of 350 Hz, the feedback resistor 80 has
a value of 1 M£2 and the capacitor 82 has a value of 1 jjF. The square wave 84 is then
applied to a paralleled inverter set 86. The square wave 84 is also applied through an

20 inverter 88 to a second paralleled inverter set 90 to produce a wave form shifted 180°
from the original square wave 84. The first paralleled inverter set output 87 is applied to
Terminal X on one side of the pzt material 42 and the second paralleled inverter set
output 91 is applied to the Terminal Y on other side of the pzt material 42. Thus, by

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applying opposite wave forms across the pzt wafer, the voltage is effectively doubled.
This circuit therefore takes the 12 volt dc power supply and converts it to a 24 volt ac
peak to peak signal This is then capable of driving the pzt material sufficiently to
produce vibrations that can be felt by the user. The input signal 56 to activate the pzt

5 material 42 is provided from the cpu or other analog circuitry (not shown). The signal
provides a switching signal 94 to the inverters 86,90. This circuit uses easily available
materials to provide a cost-effective electrical source for the pzt material; it is envisioned
that this could be done in a number of equally useful manners. Similarly, while the
preferred design uses a 24 peak to peak square wave to drive the pzt material, it would be

10 recognized by one skilled in the art that a variety of other input signals could be used. It
should also be recognized that the 24 volt signal was selected because of the relative cost-
effectiveness of doubling the power supply voltage available in the computer; however,
as the voltage increases the amplitude of the vibration would increase as well. Thus, the
amount of tactile feedback could be increased by increasing the drive voltage if that was

15 found to be desirable.

Another approach to enhance the vibration provided to the user is to mount
multiple layers of pzt material on top of each other. When properly poled layers of pzt
material are placed on top of each other, activating them in concert naturally increases the
overall effect. This can be used to provide a greater amount of vibration. This approach

20 can also be used to reduce the footprint of the pzt material required; by increasing the
vibration output through the use of multiple layers, the footprint can be reduced. This
can be useful where space limitations are critical

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The driver circuit 50 was designed to be cost-effective and to occupy minimal
space on a circuit board. A single package is readily available that includes the six
inverters required. Similarly, the circuit that generates the switching signal 94 is
available in a single integrated circuit. The remaining resistors, capacitor and diode are

5 readily available and can be mounted to occupy minimal space. Thus, this circuit was
selected to provide a simple, cost-effective driver for the pzt material.

The driver circuit also includes input suppression module 70. When the pzt
material is activated, the cursor control device will be subject to the resulting vibrations.
These vibrations will be sensed by the strain gages a,b,c,d as cursor control inputs. The

10 vibrations will therefore cause the cursor to move or jump on the display device.
Suppression module 70 senses the input signal 56 and deactivates the cursor control
signal 74 for the duration of the vibrations via suppression signal 72. After the pzt
material is stable again, the suppression signal 72 is released and the user input to the
cursor control device will again be sensed.

15 A slight modification to this system would incorporate a suppression filter. In this

approach, during tactile feedback operation, the cursor control signal is filter for the
spurious signals resulting from the tactile feedback, but the larger scale cursor control
movements are still sensed. This would simply eliminate the results of the tactile
feedback operation without interfering with the overall operation of the device.

20 It should be obvious to one of ordinary skill in the art that the suppression

function could also be performed in software. Following a mouse click input, the
software could simply ignore cursor control inputs from the cursor control device until a

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preset period of time had passed. In this way, the same function could be accomplished
without the need for any additional electronics or hardware.

An alternative arrangement is shown in Fig. 6 using a standard computer mouse
60. The mouse 60 includes two buttons 62,64. One button is configured in the computer

5 to provide a left click signal 62 and the other to provide a right click signal 64. A tactile
assembly 66 is provided internally to the mouse similar in all respects to those described
above in conjunction with the pointing stick. The precise mounting of the tactile
feedback assembly 66 including a piezo-electric material is not shown but could be
accomplished similar to the mounting described above or through any other mounting

10 mechanism that allows sufficient mechanical coupling to deliver the vibrations to the

mouse 60. Upon receiving a button click 62 or 64 signal, the piezo-electric material 68 is
activated via an ac power source. Similar to the pointing stick implementation described
previously, the power source is activated for approximately one second to provide the
tactile feedback to the user.

15 Additionally, software commonly used in computers provides "active areas."

These are various points on the screen that allow a direct link to other information or data
via user selection. For example, in Windows 98, the "desktop" screen includes icons
corresponding to a number of software applications resident on the harddrive of the
computer. The user can launch an application by placing the cursor over an icon and

20 "double-clicking" by depressing the left mouse button twice in rapid succession. The
present invention can be used to provide feedback to the user when the cursor is
positioned over an active area on the screen. So, for example, as the user moved the
cursor control device and the cursor encountered an icon on the desktop, the tactile

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feedback would be engaged to provide the user an indication of the cursor's position.
This could be done, for example, to help people with coordination or sight problems
locate the active areas on the screen.

It should be apparent that the detailed description above is illustrative only and
should not be taken as limiting the scope of the invention. Similarly, not all of the
functions performed by the embodiment disclosed need be performed in any one
mechanism or circuit. Accordingly, the invention should be understood to include all
such modifications as come within the scope and spirit of the following claims and
equivalents thereto.

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